What year? I think it's universal but I'm not sure. I'm guessing RENIX years since that's got a closed cooling system...
picked a random RENIX year out of you-know-where, came up with OEM part number 5300 4379 for an 87 and 5300 4838 for an 88-90. That's the whole hose from the valve cover to the airbox though.
I think NAPA has a full set of vac lines, including those, for a pretty good price, but I'm not sure. I seem to recall Joe Peters posting about it.